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Search Results: 1 - 10 of 32731 matches for " Daniel Weingart; "
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Obten??o de extratos de guaraná ricos em cafeína por processo enzimático e adsor??o de taninos
Ribeiro, Bernardo Dias;Coelho, Maria Alice Zarur;Barreto, Daniel Weingart;
Brazilian Journal of Food Technology , 2012, DOI: 10.1590/S1981-67232012005000020
Abstract: guarana-flavoured beverages are very popular in brazil and have shown an excellent sales potential on foreign markets. according to brazilian law, each 100 ml of guarana-flavoured beverages must contain between 0.02 g and 0.2 g of guarana seed or its equivalent. these levels are normally obtained by adding a concentrated hydroalcoholic extract or sugar syrup containing guarana extract, directly to the beverage. however, the use of more concentrated extracts is limited by the presence of tannins, which imparts astringency and a dark colour to the final product. in this work the development of an enzymatic process to obtain non-alcoholic guarana extracts with low tannin concentrations and high caffeine contents was studied using an experimental design and adsorption processes. by way of a fractional factorial design the quantities of 0.25% (v/v) pectinase and 0.1% (v/v) glucoamylase were determined, which were maintained in the central composite design, obtaining as the optimal conditions: 0.23% (v/v) cellulase, 0.86% (v/v) hemicellulase, 1% (v/v) alpha-amylase, 5.5 h extraction time, 200 rpm and 50 °c, producing a caffeine/tannin ratio of 1.65. using a magnesium oxide adsorption process at 10% (w/v), a caffeine/tannin ratio of 7.3 was obtained.
Enzyme-Enhanced Extraction of Phenolic Compounds and Proteins from Flaxseed Meal
Bernardo Dias Ribeiro,Daniel Weingart Barreto,Maria Alice Zarur Coelho
ISRN Biotechnology , 2013, DOI: 10.5402/2013/521067
Abstract:
Obten o de extratos de guaraná ricos em cafeína por processo enzimático e adsor o de taninos Production of caffeine-rich guarana extracts using an enzymatic process and tannin adsorption
Bernardo Dias Ribeiro,Maria Alice Zarur Coelho,Daniel Weingart Barreto
Brazilian Journal of Food Technology , 2012,
Abstract: As bebidas sabor guaraná s o muito populares no Brasil e têm apresentado um excelente potencial de vendas no mercado externo. De acordo com as leis brasileiras, bebidas sabor guaraná devem conter entre 0,02 g a 0,2 g de semente de guaraná ou equivalente, para cada 100 mL de produto. Tais teores s o usualmente obtidos pela adi o de um extrato concentrado hidroalcoólico ou xarope de a úcar contendo extrato de guaraná diretamente à bebida. A utiliza o desses extratos em concentra es mais elevadas, entretanto, é limitada pela presen a dos taninos, que conferem adstringência e colora o escura ao produto final. Neste trabalho, foi estudado o desenvolvimento de um processo enzimático para obten o de extratos n o alcoólicos de guaraná, de forma a produzir um extrato contendo baixas concentra es de taninos e teores elevados de cafeína, utilizando-se planejamento experimental e processos de adsor o. Por meio de um planejamento fatorial fracionário, foram determinadas as quantidades de 0,25% (v/v) de pectinase e 0,1% (v/v) de glucoamilase, sendo mantidas no planejamento composto central, que obteve como condi es ótimas: 0,23% (v/v) de celulase, 0,86% (v/v) de hemicelulase e 1% (v/v) de alfa-amilase durante 5,5 h de extra o a 200 rpm e 50 °C, obtendo-se uma rela o cafeína/tanino de 1,65. Com o processo de adsor o com óxido de magnésio a 10% (p/v), foi alcan ada uma rela o de cafeína-tanino de 7,3. Guarana-flavoured beverages are very popular in Brazil and have shown an excellent sales potential on foreign markets. According to Brazilian law, each 100 mL of guarana-flavoured beverages must contain between 0.02 g and 0.2 g of guarana seed or its equivalent. These levels are normally obtained by adding a concentrated hydroalcoholic extract or sugar syrup containing guarana extract, directly to the beverage. However, the use of more concentrated extracts is limited by the presence of tannins, which imparts astringency and a dark colour to the final product. In this work the development of an enzymatic process to obtain non-alcoholic guarana extracts with low tannin concentrations and high caffeine contents was studied using an experimental design and adsorption processes. By way of a fractional factorial design the quantities of 0.25% (v/v) pectinase and 0.1% (v/v) glucoamylase were determined, which were maintained in the central composite design, obtaining as the optimal conditions: 0.23% (v/v) cellulase, 0.86% (v/v) hemicellulase, 1% (v/v) alpha-amylase, 5.5 h extraction time, 200 rpm and 50 °C, producing a caffeine/tannin ratio of 1.65. Using a magnesiu
Enzyme-Enhanced Extraction of Phenolic Compounds and Proteins from Flaxseed Meal
Bernardo Dias Ribeiro,Daniel Weingart Barreto,Maria Alice Zarur Coelho
ISRN Biotechnology , 2013, DOI: 10.5402/2013/521067
Abstract: Flaxseed (Linum usitatissimum) meal, the main byproduct of the flaxseed oil extraction process, is composed mainly of proteins, mucilage, and phenolic compounds. The extraction methods of phenolics either commonly employed the use of mixed solvents (dioxane/ethanol, water/acetone, water/methanol, and water/ethanol) or are done with the aid of alkaline, acid, or enzymatic hydrolysis. This work aimed at the study of optimal conditions for a clean process, using renewable solvents and enzymes, for the extraction of phenolics and proteins from flaxseed meal. After a screening of the most promising commercial preparations based on different carbohydrases and proteases, a central composite rotatable design and a mixture design were applied, achieving as optimal results a solution containing 6.6 and 152?g of phenolics and proteins, respectively. The statistical approach used in the present study for the enzyme-enhanced extraction of phenolics and proteins from the major flaxseed byproduct was effective. By means of the sequential experimental design methodology, the extraction of such compounds was increased 10-fold and 14-fold, when compared to a conventional nonenzymatic extraction. 1. Introduction Flaxseed (Linum usitatissimum) meal is the main byproduct from the flaxseed oil extraction process, being primarily used as a ruminant feed. The meal is composed of three important fractions: proteins (over 300?g?kg?1), which are rich in arginine and glutamine; amino acids that are very important in the prevention and treatment of heart diseases and in supporting the immune system; mucilage (approximate content of 80?g?kg?1), which is a mixture of neutral arabinoxylans and rhamnogalacturonans, with good water-holding capacities and high viscosity; phenolic compounds, such as p-coumaric and ferulic acids, lignan secoisolariciresinol, which is presented glycosylated (Figure 1) and/or esterified with 3-hydroxy-3-methylglutaric acid to form oligomers. The content of secoisolariciresinol diglucoside in flaxseed is 2-3?g?kg?1, and about 10–40?g?kg?1 in defatted flaxseed powder [1–5]. Figure 1: Lignan secoisolariciresinol diglucoside. In humans and animals, secoisolariciresinol is transformed by the anaerobic intestinal microflora into the mammalian lignans, enterolactone, and enterodiol, which are capable of binding at low levels to estrogen receptors. Additionally, these lignans have antioxidant, hypocholesterolemic, and antiatherosclerotic activities and inhibit the development of type 1 and type 2 diabetes, and mammary, prostatic, and colonic tumors [3, 6–9]. Lignans
Chemists and their Craft in Fiction Film
Peter Weingart
Hyle : International Journal for Philosophy of Chemistry , 2006,
Abstract: The paper presents results from a quantitative analysis of some 200 fiction films. Chemistry is the iconic discipline of the 'mad scientist' reflecting the alchemical imagery that was prevalent until recently (and can still be identified) in the depiction of science in films. Other results show the ambivalence with which primarily the natural sciences are represented in popular movies.
"Demokratisierung des Zugangs zu Wissen."
Weingart, Peter
Zeitenblicke , 2006,
Abstract:
The QCD rotator with a light quark mass
Manuel Weingart
Physics , 2010,
Abstract: The low-lying energy excitations of 2-flavour QCD in the chiral limit confined to a small spatial box ($\delta$-regime) are that of an $O(4)$ rotator. In this work, we calculate the corrections due to the presence of a nonzero quark mass up to NNL order by means of dimensional regularised chiral perturbation theory. The final result for the energy gap of the system only involves the low-energy constants $F$, $\Lambda_1$, $\Lambda_2$ and $B$.
A Characterization of the Heat Kernel Coefficients
Gregor Weingart
Mathematics , 2001,
Abstract: We consider the asymptotic expansion of the heat kernel of a generalized Laplacian for $t\to 0^+$ and characterize the coefficients $a_k$ of this expansion by a natural intertwining property. In particular we will give a closed formula for the infinite order jet of these coefficients on the diagonal in terms of the local expressions of the powers of the given generalized Laplacian in normal coordinates.
An ethanol-based process to simultaneously extract and fractionate carotenoids from Mauritia flexuosa L. Pulp
Ribeiro, Bernardo Dias;Nascimento, Rafaella Ferreira;Barreto, Daniel Weingart;Coelho, Maria Alice Zarur;Freitas, Suely Pereira;
Revista Brasileira de Fruticultura , 2010, DOI: 10.1590/S0100-29452010005000099
Abstract: mauritia vinifera (buriti) is a palm tree that grows wild in different areas of brazil, particularly in the amazonian region. the buriti oil is rich in carotenoids, especially in β-carotene. the growing interest in other natural sources of β-carotene has stimulated the industrial use of buriti as a raw material for pulp oil extraction. most processes are based on the conventional technologies, involving drying and pressing the pulp for oil recovery and further separation of carotenoids in a liquid phase using organics solvents. in the present work, the ethanol-based process was evaluated for simultaneous carotenoids recovering and fractionating from buriti pulp. the raw material and ethanol, 1:4 ratio, were placed in an erlenmeyer flask and maintained at 30rpm for 1 hour in a temperature-controlled bath at 65oc. the mixture was filtered under vacuum and cooling at 10oc to allow for the separation of the solvent in two phases. carotenoids composition, determined by hplc, has indicated a β-carotene concentration about 12 times greater in the lower phase than in the upper phase. the profile of the carotenoids in the denser phase is quite similar to that of raw buriti oil, and the concentration of total carotenoids is 40% higher than that of the original raw oil, making the ethanol-based process particularly attractive for industrial applications.
Enhanced expression of codon optimized Mycobacterium avium subsp. paratuberculosis antigens in Lactobacillus salivarius
Christopher D. Johnston,John P. Bannantine,Daniel Pletzer,Helge Weingart,Aidan Coffey,Jim O'Mahony,Roy D. Sleator
Frontiers in Cellular and Infection Microbiology , 2014, DOI: 10.3389/fcimb.2014.00120
Abstract: It is well documented that open reading frames containing high GC content show poor expression in A+T rich hosts. Specifically, G+C-rich codon usage is a limiting factor in heterologous expression of Mycobacterium avium subsp. paratuberculosis (MAP) proteins using Lactobacillus salivarius. However, re-engineering opening reading frames through synonymous substitutions can offset codon bias and greatly enhance MAP protein production in this host. In this report, we demonstrate that codon-usage manipulation of MAP2121c can enhance the heterologous expression of the major membrane protein (MMP), analogous to the form in which it is produced natively by MAP bacilli. When heterologously over-expressed, antigenic determinants were preserved in synthetic MMP proteins as shown by monoclonal antibody mediated ELISA. Moreover, MMP is a membrane protein in MAP, which is also targeted to the cellular surface of recombinant L. salivarius at levels comparable to MAP. Additionally, we previously engineered MAP3733c (encoding MptD) and show herein that MptD displays the tendency to associate with the cytoplasmic membrane boundary under confocal microscopy and the intracellularly accumulated protein selectively adheres to the MptD-specific bacteriophage fMptD. This work demonstrates there is potential for L. salivarius as a viable antigen delivery vehicle for MAP, which may provide an effective mucosal vaccine against Johne's disease.
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